The locking ring software is well developed, but requires that your Judge
Dredd be working correctly. There are two trouble spots: the ball trough, and
the crane mechanism. The planet can also be trouble, but we'll assume that that
is working.

The machine here has been through some ham-handed repairs. At some point, it
looks like someone pretty good worked on it. However, a later tech just gave up
and marked the lockdown bar holder with "3 balls". The crane mechanism has had
the typical Judge Dredd wreck where the crane catches on the cabinet when raised
or lowered. The swivel rod had been replaced with aluminum, and badly bent. The
opto wheels had all been overtightened so that the threads broke out. And there
was so much slop in the mechanism that the crane had a hard time working.

The crane is designed with flats on all shafts, so the lever arm eccentric
and the crane arm are
self-aligning. If all the parts are OK, and the crane is assembled properly -
which is simple - it should work. There are two adjustments - the position of
the lifter wheel on the crane shaft, and the height of the crane. There are still a few things that can get you, however. In
servicing the crane, your goal is to get the arm motion tight with little slop,
and to get the arm positioned over the ball. If the ball clears the plastic, the
magnet has enough pull to snap it to its pole. if the plastic interferes, you
will get a weak hold and a drop down the front. Arm height is important, and go
for a little high rather than a little low. Don't forget to tighten the locknut
on the height adjustment.

This piece fits on top of the swivel shaft. The crane arm mounts to it with a
pin, held in by 3/16 e clips. The screw should hold the flat so that the
mounting bracket is parallel with the flat on the shaft. The collar is peened
onto the bracket.

On
this machine, the peened edge is too lose. The crane arm has too much play - you
can test this by rotating the crane from side to side. It should not move much.
If it does, check that the screw is tight (you will have a set screw). If it
still moves, look to see if the bracket is rotating against the collar. I have
these on
Pinbits, or you can try to stake the two parts together with a hammer. I did
best with a replacement part.

That's not the original screw.

Problem #2 - planet slop

These
two pictures show how much slop my planet has. The gearbox is worn. I am not
going to fix this, the mechanism can accommodate it.

Problem #3 - eccentric and lifter wheel

This
wheel lifts the arm, and tells the opto interruptor when the arm is over the
magnet. Mine is all busted up, and that clip is a new addition. I have secured a
few spares - up on
Pinbits.

There is one tuning opportunity. The wheel is set so that, when the crane is
fully lowered, the opto is active. This is the point at which the game will
activate the magnet. By adjusting the position of the wheel on the shaft, you
can set it so that the crane is fully lowered just as the crane reverses its
travel. This has the effect of lengthening the time
that the magnet carries the ball for. It is an important adjustment, as the
carry time is short, and if you are on the wrong side of correct the magnet will
drop the ball before it is all the way back. Note that the slot is between the interruptors at 9 o'clock, and the eccentric shaft is at about 11:45.

The eccentric arm wears. That causes slop in the arm movement, which messes
up ball drops. My machine was missing its bearing, so I made a new, slightly
larger, one out of a bronze sleeve bearing from our local hardware store. (I did eventually find the original in the
cabinet). The washer and e-clip are not original. But
I feel more comfortable with them on there. I also have the arm on upside down:
my new sleeve rides in the worn slot better that way.

Step-by Step Instructions for Adjusting the Lifter Wheel

1) Raise the playfield to vertical and loosen the lifter wheel set screw so
that you can rotate it by hand, but so that it stays where you put it.

2) Put the playfield in the down but forward position, so you can reach the
wheel behind the backbox - I did this from the left hand side of the machine.

3) Reach down and turn the wheel a fraction. Then use the test mode to run the
arm (you'll probably need to go into test 16, and then back to 15). The arm
should stop in a different position.

4) Adjust the wheel until the arm stops after it drops, and just starts to rise.
This will take a few goes.

5) When you think that it is correct, lower the playfield and run the planet
unload test. If that works, secure the set screw and you are done.

The
eccentric will straighten up when on its shaft Note the large screw that barely
holds the wheel to the shaft. That steel clip is now doing all the work. New
parts have a threaded insert and a set screw.

Problem #4 - Upper washer stack

The
top side of the shaft is supposed to have a washer and e-ring to hold the arm
up. mine did not even have a groove. Here's the new shaft with a PTFE and steel
washer.

Problem #5 - Beat-Up Crane

I have had reports of crane arms where the metal is twisted, so that the
alignment is off. This problem happens because of the playfield being lifted
with the crane caught on the edge of the machine. It also busts up the crane
plastic cover. You'll need to hammer and bend to get it straightened out; it
cannot be adjusted.

Note how the ball snaps onto the ring. That snap is the key to a strong hold.
Also note how the first two balls are drawn to the magnet: the slop in the ring
causes that jump. The third ball is a clean pick. The weight of the balls causes
the ring to end up in slightly different positions.